1. Field of the Invention
The present invention relates to an epoxy resin composition, a cured article thereof, a novel epoxy resin used in the same, a polyhydric phenol compound suited for use as an intermediate thereof, and a process for preparing the same.
2. Description of Related Art
Thermosetting resin compositions comprising an epoxy resin and a curing agent have widely been used as electric or electronic materials such as semiconductor encapsulating materials and varnishes for circuit boards.
Recently, in the field of semiconductors, although one-surface sealed type packages such as a ball grid array type semiconductor have widely been used, these arises a large problem such as warp of the package after molding. To solve the problem, a sealing resin having a high glass transition temperature is now required. Also in the field of circuit boards, a material having a high glass transition temperature is strongly desired as a means for enhancing the dimensional stability of a multi-layer laminated board.
To improve the heat resistance of a cured article of an epoxy resin, a crosslinking density of the cured article is generally increased. Therefore, it is necessary to increase the concentration of epoxy groups in the epoxy resin. However, according to such a means, the cured article has a lot of secondary hydroxyl groups derived from epoxy groups, thereby impairing properties required of the semiconductor encapsulating material and varnish for circuit boards, for example, moisture resistance and low constant.
For example, Japanese Patent Application, First publication No. Hei 8-27250 and Japanese Patent Application, First publication No. Hei 9-48839 disclose techniques of using a dicyclopentadiene type epoxy resin as an epoxy resin for semiconductor encapsulating materials having excellent heat resistance of the cured article without impairing required properties such as moisture resistance and low constant.
Although the dicyclopentadiene type epoxy resin disclosed in Japanese Patent Application, First Publication No. Hei 8-27250 or Japanese Patent Application, First Publication No. Hei 9-48839 has excellent performances as a semiconductor encapsulating material, for example, excellent heat resistance, water resistance and dielectric properties of the cured article, the use of an additive-based flame retardant such as halogen-based flame retardant or phosphorus-based flame retardant cannot be avoided when used because the dicyclopentadiene type epoxy resin is easy to burn. On the other hand, the halogen-based flame retardant is a factor capable of generating dioxin, while the phosphorus-based flame retardant has a problem of lowering the hydrolytic resistance, in addition to its toxicity. Therefore, an epoxy resin composition has been desired wherein the flame resistance is imparted to the epoxy resin itself without impairing the required properties described above.
An object to be achieved by the present invention is to exert the heat resistance, the moisture resistance, the dielectric performances and the flame-resistant effect required of electric or electronic materials such as semiconductor encapsulating materials and varnishes for circuit boards in the epoxy resin composition.
Another object to be achieved by the present invention is to provide a novel epoxy resin having excellent heat resistance, moisture resistance, dielectric performances and flame-resistant effects.
Still another object to be achieved by the present invention is to provide a phenol compound suited for use as an intermediate of the novel epoxy resin.
To achieve the objects described above, the present inventors have intensively researched and have found that the flame resistance is markedly improved, in addition to the heat resistance, the moisture resistance and the dielectric properties, by introducing, as a structure constituting a repeating unit of an epoxy resin structure, an aromatic polycyclic structure, in which two aromatic hydrocarbons are bonded through carbon atoms or oxygen atoms in two adjacent substitution positions on an aromatic ring in the aromatic hydrocarbon, into the epoxy resin structure. Thus, the present invention has been completed.
The present invention relates to an epoxy resin composition comprising an epoxy resin and a curing agent, wherein the epoxy resin has an aromatic polycyclic structure in which two aromatic hydrocarbons are bonded through carbon atoms or oxygen atoms in two adjacent substitution positions on an aromatic ring in the aromatic hydrocarbon, and also has glycidyloxy groups as a substituent on the aromatic polycyclic structure.
Another aspect of the invention relates to a novel epoxy resin represented by the general formula (1): 
in the general formula (1), X represents oxygen atom, a methylene group, a methylene group substituted with an alkyl group having 1 to 4 carbon atoms, a methylene group substituted with a phenyl group, a methylene group substituted with a naphthyl group, a methylene group substituted with a biphenyl group, a methylene group substituted with a 9-fluorenyl group, or a methylene group in which an alkyl group is further aromatic nucleus-substituted on the phenyl group, the naphthyl group or the biphenyl group, n and m represent an integer of 0 to 3, and p represents an average repeated unit number of 0 to 10.
Still another aspect of the invention relates to a novel epoxy resin represented by the general formula (2): 
in the general formula (2), X represents oxygen atom, a methylene group, a methylene group substituted with an alkyl group having 1 to 4 carbon atoms, a methylene group substituted with a phenyl group, a methylene group substituted with a naphthyl group, a methylene group substituted with a biphenyl group, a methylene group substituted with a 9-fluorenyl group, or a methylene group in which an alkyl group is further aromatic nucleus-substituted on the phenyl group, the naphthyl group or the biphenyl group, n and m represents an integer of 0 to 5, and p represents an average repeated unit number of 0 to 10.
A further aspect of the invention relates to a novel phenol compound represented by the general formula (3): 
in the general formula (3), X represents oxygen atom, a methylene group, a methylene group substituted with an alkyl group, a methylene group substituted with a phenyl group, a methylene group substituted with a naphthyl group, a methylene group substituted with a biphenyl group, a methylene group substituted with a 9-fluorenyl group, or a methylene group in which an alkyl group is further aromatic nucleus-substituted on the phenyl group, the naphthyl group or the biphenyl group, and n and m represent an integer of 0 to 3.
A still further aspect of the invention relates to a novel phenol compound represented by the general formula (4): 
in the general formula (4), X represents oxygen atom, a methylene group, a methylene group substituted with an alkyl group, a methylene group substituted with a phenyl group, a methylene group substituted with a naphthyl group, a methylene group substituted with a biphenyl group, a methylene group substituted with a 9-fluorenyl group, or a methylene group in which an alkyl group is further aromatic nucleus-substituted on the phenyl group, the naphthyl group or the biphenyl group, and n and m represent an integer of 0 to 5.
Another aspect of the invention relates to a process for preparing a polyhydric hydroxy compound, which comprises reacting a compound having two hydroxyl groups on the benzene ring, one of the hydroxyl groups having a hydrogen atom at the ortho-position and a substituent at all of the other substitution positions, with a carbonyl group-containing compound in the presence of an acid catalyst.
A further invention relates to a cured article obtained by thermally curing the epoxy composition.